1 /* Netfilter messages via netlink socket. Allows for user space 2 * protocol helpers and general trouble making from userspace. 3 * 4 * (C) 2001 by Jay Schulist <jschlst@samba.org>, 5 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org> 6 * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org> 7 * 8 * Initial netfilter messages via netlink development funded and 9 * generally made possible by Network Robots, Inc. (www.networkrobots.com) 10 * 11 * Further development of this code funded by Astaro AG (http://www.astaro.com) 12 * 13 * This software may be used and distributed according to the terms 14 * of the GNU General Public License, incorporated herein by reference. 15 */ 16 17 #include <linux/module.h> 18 #include <linux/types.h> 19 #include <linux/socket.h> 20 #include <linux/kernel.h> 21 #include <linux/string.h> 22 #include <linux/sockios.h> 23 #include <linux/net.h> 24 #include <linux/skbuff.h> 25 #include <asm/uaccess.h> 26 #include <net/sock.h> 27 #include <linux/init.h> 28 29 #include <net/netlink.h> 30 #include <linux/netfilter/nfnetlink.h> 31 32 MODULE_LICENSE("GPL"); 33 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 34 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 35 36 static char __initdata nfversion[] = "0.30"; 37 38 static struct { 39 struct mutex mutex; 40 const struct nfnetlink_subsystem __rcu *subsys; 41 } table[NFNL_SUBSYS_COUNT]; 42 43 static const int nfnl_group2type[NFNLGRP_MAX+1] = { 44 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, 45 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, 46 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, 47 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, 48 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, 49 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, 50 [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES, 51 [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT, 52 }; 53 54 void nfnl_lock(__u8 subsys_id) 55 { 56 mutex_lock(&table[subsys_id].mutex); 57 } 58 EXPORT_SYMBOL_GPL(nfnl_lock); 59 60 void nfnl_unlock(__u8 subsys_id) 61 { 62 mutex_unlock(&table[subsys_id].mutex); 63 } 64 EXPORT_SYMBOL_GPL(nfnl_unlock); 65 66 #ifdef CONFIG_PROVE_LOCKING 67 int lockdep_nfnl_is_held(u8 subsys_id) 68 { 69 return lockdep_is_held(&table[subsys_id].mutex); 70 } 71 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); 72 #endif 73 74 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 75 { 76 nfnl_lock(n->subsys_id); 77 if (table[n->subsys_id].subsys) { 78 nfnl_unlock(n->subsys_id); 79 return -EBUSY; 80 } 81 rcu_assign_pointer(table[n->subsys_id].subsys, n); 82 nfnl_unlock(n->subsys_id); 83 84 return 0; 85 } 86 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 87 88 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 89 { 90 nfnl_lock(n->subsys_id); 91 table[n->subsys_id].subsys = NULL; 92 nfnl_unlock(n->subsys_id); 93 synchronize_rcu(); 94 return 0; 95 } 96 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 97 98 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 99 { 100 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 101 102 if (subsys_id >= NFNL_SUBSYS_COUNT) 103 return NULL; 104 105 return rcu_dereference(table[subsys_id].subsys); 106 } 107 108 static inline const struct nfnl_callback * 109 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 110 { 111 u_int8_t cb_id = NFNL_MSG_TYPE(type); 112 113 if (cb_id >= ss->cb_count) 114 return NULL; 115 116 return &ss->cb[cb_id]; 117 } 118 119 int nfnetlink_has_listeners(struct net *net, unsigned int group) 120 { 121 return netlink_has_listeners(net->nfnl, group); 122 } 123 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 124 125 struct sk_buff *nfnetlink_alloc_skb(struct net *net, unsigned int size, 126 u32 dst_portid, gfp_t gfp_mask) 127 { 128 return netlink_alloc_skb(net->nfnl, size, dst_portid, gfp_mask); 129 } 130 EXPORT_SYMBOL_GPL(nfnetlink_alloc_skb); 131 132 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, 133 unsigned int group, int echo, gfp_t flags) 134 { 135 return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags); 136 } 137 EXPORT_SYMBOL_GPL(nfnetlink_send); 138 139 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) 140 { 141 return netlink_set_err(net->nfnl, portid, group, error); 142 } 143 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 144 145 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid, 146 int flags) 147 { 148 return netlink_unicast(net->nfnl, skb, portid, flags); 149 } 150 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 151 152 /* Process one complete nfnetlink message. */ 153 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 154 { 155 struct net *net = sock_net(skb->sk); 156 const struct nfnl_callback *nc; 157 const struct nfnetlink_subsystem *ss; 158 int type, err; 159 160 /* All the messages must at least contain nfgenmsg */ 161 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg)) 162 return 0; 163 164 type = nlh->nlmsg_type; 165 replay: 166 rcu_read_lock(); 167 ss = nfnetlink_get_subsys(type); 168 if (!ss) { 169 #ifdef CONFIG_MODULES 170 rcu_read_unlock(); 171 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 172 rcu_read_lock(); 173 ss = nfnetlink_get_subsys(type); 174 if (!ss) 175 #endif 176 { 177 rcu_read_unlock(); 178 return -EINVAL; 179 } 180 } 181 182 nc = nfnetlink_find_client(type, ss); 183 if (!nc) { 184 rcu_read_unlock(); 185 return -EINVAL; 186 } 187 188 { 189 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 190 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 191 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 192 struct nlattr *attr = (void *)nlh + min_len; 193 int attrlen = nlh->nlmsg_len - min_len; 194 __u8 subsys_id = NFNL_SUBSYS_ID(type); 195 196 err = nla_parse(cda, ss->cb[cb_id].attr_count, 197 attr, attrlen, ss->cb[cb_id].policy); 198 if (err < 0) { 199 rcu_read_unlock(); 200 return err; 201 } 202 203 if (nc->call_rcu) { 204 err = nc->call_rcu(net->nfnl, skb, nlh, 205 (const struct nlattr **)cda); 206 rcu_read_unlock(); 207 } else { 208 rcu_read_unlock(); 209 nfnl_lock(subsys_id); 210 if (rcu_dereference_protected(table[subsys_id].subsys, 211 lockdep_is_held(&table[subsys_id].mutex)) != ss || 212 nfnetlink_find_client(type, ss) != nc) 213 err = -EAGAIN; 214 else if (nc->call) 215 err = nc->call(net->nfnl, skb, nlh, 216 (const struct nlattr **)cda); 217 else 218 err = -EINVAL; 219 nfnl_unlock(subsys_id); 220 } 221 if (err == -EAGAIN) 222 goto replay; 223 return err; 224 } 225 } 226 227 struct nfnl_err { 228 struct list_head head; 229 struct nlmsghdr *nlh; 230 int err; 231 }; 232 233 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err) 234 { 235 struct nfnl_err *nfnl_err; 236 237 nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL); 238 if (nfnl_err == NULL) 239 return -ENOMEM; 240 241 nfnl_err->nlh = nlh; 242 nfnl_err->err = err; 243 list_add_tail(&nfnl_err->head, list); 244 245 return 0; 246 } 247 248 static void nfnl_err_del(struct nfnl_err *nfnl_err) 249 { 250 list_del(&nfnl_err->head); 251 kfree(nfnl_err); 252 } 253 254 static void nfnl_err_reset(struct list_head *err_list) 255 { 256 struct nfnl_err *nfnl_err, *next; 257 258 list_for_each_entry_safe(nfnl_err, next, err_list, head) 259 nfnl_err_del(nfnl_err); 260 } 261 262 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb) 263 { 264 struct nfnl_err *nfnl_err, *next; 265 266 list_for_each_entry_safe(nfnl_err, next, err_list, head) { 267 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err); 268 nfnl_err_del(nfnl_err); 269 } 270 } 271 272 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, 273 u_int16_t subsys_id) 274 { 275 struct sk_buff *nskb, *oskb = skb; 276 struct net *net = sock_net(skb->sk); 277 const struct nfnetlink_subsystem *ss; 278 const struct nfnl_callback *nc; 279 bool success = true, done = false; 280 static LIST_HEAD(err_list); 281 int err; 282 283 if (subsys_id >= NFNL_SUBSYS_COUNT) 284 return netlink_ack(skb, nlh, -EINVAL); 285 replay: 286 nskb = netlink_skb_clone(oskb, GFP_KERNEL); 287 if (!nskb) 288 return netlink_ack(oskb, nlh, -ENOMEM); 289 290 nskb->sk = oskb->sk; 291 skb = nskb; 292 293 nfnl_lock(subsys_id); 294 ss = rcu_dereference_protected(table[subsys_id].subsys, 295 lockdep_is_held(&table[subsys_id].mutex)); 296 if (!ss) { 297 #ifdef CONFIG_MODULES 298 nfnl_unlock(subsys_id); 299 request_module("nfnetlink-subsys-%d", subsys_id); 300 nfnl_lock(subsys_id); 301 ss = rcu_dereference_protected(table[subsys_id].subsys, 302 lockdep_is_held(&table[subsys_id].mutex)); 303 if (!ss) 304 #endif 305 { 306 nfnl_unlock(subsys_id); 307 netlink_ack(skb, nlh, -EOPNOTSUPP); 308 return kfree_skb(nskb); 309 } 310 } 311 312 if (!ss->commit || !ss->abort) { 313 nfnl_unlock(subsys_id); 314 netlink_ack(skb, nlh, -EOPNOTSUPP); 315 return kfree_skb(skb); 316 } 317 318 while (skb->len >= nlmsg_total_size(0)) { 319 int msglen, type; 320 321 nlh = nlmsg_hdr(skb); 322 err = 0; 323 324 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg) || 325 skb->len < nlh->nlmsg_len) { 326 err = -EINVAL; 327 goto ack; 328 } 329 330 /* Only requests are handled by the kernel */ 331 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { 332 err = -EINVAL; 333 goto ack; 334 } 335 336 type = nlh->nlmsg_type; 337 if (type == NFNL_MSG_BATCH_BEGIN) { 338 /* Malformed: Batch begin twice */ 339 nfnl_err_reset(&err_list); 340 success = false; 341 goto done; 342 } else if (type == NFNL_MSG_BATCH_END) { 343 done = true; 344 goto done; 345 } else if (type < NLMSG_MIN_TYPE) { 346 err = -EINVAL; 347 goto ack; 348 } 349 350 /* We only accept a batch with messages for the same 351 * subsystem. 352 */ 353 if (NFNL_SUBSYS_ID(type) != subsys_id) { 354 err = -EINVAL; 355 goto ack; 356 } 357 358 nc = nfnetlink_find_client(type, ss); 359 if (!nc) { 360 err = -EINVAL; 361 goto ack; 362 } 363 364 { 365 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 366 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 367 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 368 struct nlattr *attr = (void *)nlh + min_len; 369 int attrlen = nlh->nlmsg_len - min_len; 370 371 err = nla_parse(cda, ss->cb[cb_id].attr_count, 372 attr, attrlen, ss->cb[cb_id].policy); 373 if (err < 0) 374 goto ack; 375 376 if (nc->call_batch) { 377 err = nc->call_batch(net->nfnl, skb, nlh, 378 (const struct nlattr **)cda); 379 } 380 381 /* The lock was released to autoload some module, we 382 * have to abort and start from scratch using the 383 * original skb. 384 */ 385 if (err == -EAGAIN) { 386 nfnl_err_reset(&err_list); 387 ss->abort(oskb); 388 nfnl_unlock(subsys_id); 389 kfree_skb(nskb); 390 goto replay; 391 } 392 } 393 ack: 394 if (nlh->nlmsg_flags & NLM_F_ACK || err) { 395 /* Errors are delivered once the full batch has been 396 * processed, this avoids that the same error is 397 * reported several times when replaying the batch. 398 */ 399 if (nfnl_err_add(&err_list, nlh, err) < 0) { 400 /* We failed to enqueue an error, reset the 401 * list of errors and send OOM to userspace 402 * pointing to the batch header. 403 */ 404 nfnl_err_reset(&err_list); 405 netlink_ack(skb, nlmsg_hdr(oskb), -ENOMEM); 406 success = false; 407 goto done; 408 } 409 /* We don't stop processing the batch on errors, thus, 410 * userspace gets all the errors that the batch 411 * triggers. 412 */ 413 if (err) 414 success = false; 415 } 416 417 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 418 if (msglen > skb->len) 419 msglen = skb->len; 420 skb_pull(skb, msglen); 421 } 422 done: 423 if (success && done) 424 ss->commit(oskb); 425 else 426 ss->abort(oskb); 427 428 nfnl_err_deliver(&err_list, oskb); 429 nfnl_unlock(subsys_id); 430 kfree_skb(nskb); 431 } 432 433 static void nfnetlink_rcv(struct sk_buff *skb) 434 { 435 struct nlmsghdr *nlh = nlmsg_hdr(skb); 436 int msglen; 437 438 if (nlh->nlmsg_len < NLMSG_HDRLEN || 439 skb->len < nlh->nlmsg_len) 440 return; 441 442 if (!netlink_net_capable(skb, CAP_NET_ADMIN)) { 443 netlink_ack(skb, nlh, -EPERM); 444 return; 445 } 446 447 if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) { 448 struct nfgenmsg *nfgenmsg; 449 450 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 451 if (msglen > skb->len) 452 msglen = skb->len; 453 454 if (nlh->nlmsg_len < NLMSG_HDRLEN || 455 skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) 456 return; 457 458 nfgenmsg = nlmsg_data(nlh); 459 skb_pull(skb, msglen); 460 nfnetlink_rcv_batch(skb, nlh, nfgenmsg->res_id); 461 } else { 462 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 463 } 464 } 465 466 #ifdef CONFIG_MODULES 467 static int nfnetlink_bind(struct net *net, int group) 468 { 469 const struct nfnetlink_subsystem *ss; 470 int type; 471 472 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) 473 return 0; 474 475 type = nfnl_group2type[group]; 476 477 rcu_read_lock(); 478 ss = nfnetlink_get_subsys(type); 479 rcu_read_unlock(); 480 if (!ss) 481 request_module("nfnetlink-subsys-%d", type); 482 return 0; 483 } 484 #endif 485 486 static int __net_init nfnetlink_net_init(struct net *net) 487 { 488 struct sock *nfnl; 489 struct netlink_kernel_cfg cfg = { 490 .groups = NFNLGRP_MAX, 491 .input = nfnetlink_rcv, 492 #ifdef CONFIG_MODULES 493 .bind = nfnetlink_bind, 494 #endif 495 }; 496 497 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); 498 if (!nfnl) 499 return -ENOMEM; 500 net->nfnl_stash = nfnl; 501 rcu_assign_pointer(net->nfnl, nfnl); 502 return 0; 503 } 504 505 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 506 { 507 struct net *net; 508 509 list_for_each_entry(net, net_exit_list, exit_list) 510 RCU_INIT_POINTER(net->nfnl, NULL); 511 synchronize_net(); 512 list_for_each_entry(net, net_exit_list, exit_list) 513 netlink_kernel_release(net->nfnl_stash); 514 } 515 516 static struct pernet_operations nfnetlink_net_ops = { 517 .init = nfnetlink_net_init, 518 .exit_batch = nfnetlink_net_exit_batch, 519 }; 520 521 static int __init nfnetlink_init(void) 522 { 523 int i; 524 525 for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++) 526 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE); 527 528 for (i=0; i<NFNL_SUBSYS_COUNT; i++) 529 mutex_init(&table[i].mutex); 530 531 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 532 return register_pernet_subsys(&nfnetlink_net_ops); 533 } 534 535 static void __exit nfnetlink_exit(void) 536 { 537 pr_info("Removing netfilter NETLINK layer.\n"); 538 unregister_pernet_subsys(&nfnetlink_net_ops); 539 } 540 module_init(nfnetlink_init); 541 module_exit(nfnetlink_exit); 542